Querol / Fleet Yeasts in Food and Beverages

1. Auflage 2006
ISBN: 978-3-540-28398-0
Verlag: Springer Berlin Heidelberg
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 453 Seiten

Reihe: The Yeast Handbook

As a group of microorganisms, yeasts have an enormous impact on food and bev- age production. Scientific and technological understanding of their roles in this p- duction began to emerge in the mid-1800s, starting with the pioneering studies of Pasteur in France and Hansen in Denmark on the microbiology of beer and wine fermentations. Since that time, researchers throughout the world have been engaged in a fascinating journey of discovery and development - learning about the great diversity of food and beverage commodities that are produced or impacted by yeast activity, about the diversity of yeast species associated with these activities, and about the diversity of biochemical, physiological and molecular mechanisms that underpin the many roles of yeasts in food and beverage production. Many excellent books have now been published on yeasts in food and beverage production, and it is reasonable to ask the question - why another book? There are two different approaches to describe and understand the role of yeasts in food and beverage production. One approach is to focus on the commodity and the technology of its processing (e. g. wine fermentation, fermentation of bakery products), and this is the direction that most books on food and beverage yeasts have taken, to date. A second approach is to focus on the yeasts, themselves, and their bi- ogy in the context of food and beverage habitats.

Amparo Querol is a Research scientist in the Food Biotechnology Department of the Institute of Agrochemistry and Food Technology (Spanish Council for Scientific Research) and Assistant Professor Food Science and Technologiy at the University of Valencia, Spain. Her research interests include food biotechnology, genomics, systematics, phylogeny and molecular evolution of industrial yeasts. Graham Fleet is a Professor within the Food Science and Technology Unit, at the University of New South Wales. He has been active as a teacher and researcher in the fields of food microbiology, food biotechnology and yeast technology since 1975 and has authored numerous publications, reviews and books on the occurrence and significance of yeasts in food and beverage production.

Autoren/Hrsg.

Querol, Amparo

Fleet, Graham H.

Inhaltsverzeichnis

1;Preface;6
2;Contents;8
3;1 The Commercial and Community Significance of Yeasts in Food and Beverage Production;10
3.1;1.1 Introduction;10
3.2;1.2 The Informative Process;11
3.3;1.3 Production of Fermented Foods and Beverages;11
3.4;1.4 Yeasts as Sources of Ingredients and Additives for Food Processing;13
3.5;1.5 Spoilage of Foods and Beverages by Yeasts;14
3.6;1.6 Yeasts as Biocontrol Agents;15
3.7;1.7 Public Health Significance of Yeasts in Foods and Beverages;16
3.8;1.8 Probiotic Yeasts;17
3.9;1.9 Future Prospects;17
3.10;References;17
4;2 Taxonomic and Ecological Diversity of Food and Beverage Yeasts;22
4.1;2.1 Introduction;22
4.2;2.2 Yeasts in Dairy Products;23
4.3;2.3 Yeasts in Fermented Sausages;26
4.4;2.4 Yeasts in Sourdough Breads;29
4.5;2.5 Yeasts in Grape Wines;33
4.6;2.6 Yeasts in Brewing;43
4.7;2.7 Yeasts in Other Alcoholic Beverages (Cider, Sherry Wine, Tequila);45
4.8;2.8 Yeasts in Indigenous Foods, Beverages and Cash Crops;48
4.9;2.9 Collections of Food Yeast Cultures;51
4.10;References;52
5;3 Molecular Methods to Identify and Characterize Yeasts in Foods and Beverages;63
5.1;3.1 Introduction;63
5.2;3.2 Methods for Species Identification;65
5.3;3.3 Methods to Differentiate at Strain Level;74
5.4;Acknowledgements;83
5.5;References;83
6;4 Yeast Ecological Interactions. Yeast–Yeast, Yeast–Bacteria, Yeast–Fungi Interactions and Yeasts as Biocontrol Agents;91
6.1;4.1 Introduction;91
6.2;4.2 Ecological Interaction Between Microorganisms;92
6.3;4.3 Yeast Interactions in Foods and Beverages;96
6.4;4.4 Yeast Antagonism Applied as Biocontrol Agents in Preventing Plant-Spoilage Fungi;107
6.5;References;109
7;5 Physiological and Molecular Responses of Yeasts to the Environment;119
7.1;5.1 Introduction;119
7.2;5.2 Yeast Nutrition and Growth;120
7.3;5.3 Yeast Responses to Physical Stresses;128
7.4;5.4 Yeast Responses to the Chemical Environment;140
7.5;5.5 Summary and Conclusions;151
7.6;References;152
8;6 Molecular Mechanisms Involved in the Adaptive Evolution of Industrial Yeasts;161
8.1;6.1 Introduction;161
8.2;6.2 The Saccharomyces sensu stricto Complex Includes the Most Important Industrial Yeasts;162
8.3;6.3 Adaptive Evolution by “Genome Renewal”;163
8.4;6.4 Molecular Mechanisms Involved in the Generation of Evolutionary Novelties;164
8.5;6.5 Gross Chromosomal Rearrangements in Yeast Evolution;176
8.6;Acknowledgements;177
8.7;References;178
9;7 Principles and Applications of Genomics and Proteomics in the Analysis of Industrial Yeast Strains;183
9.1;7.1 Introduction;183
9.2;7.2 DNA Sequencing of Yeast Genomes;183
9.3;7.3 Whole Genome Approaches to the Characterisation of Industrial Strains of Yeasts;185
9.4;7.4 Genome Constitution of Industrial Strains of Yeasts;196
9.5;7.5 Analyses of the Industrial Process;208
9.6;7.6 Future Perspectives;214
9.7;References;215
10;8 Carbohydrate Metabolism;222
10.1;8.1 Introduction;222
10.2;8.2 Carbon Sources;222
10.3;8.3 Modes of Metabolism;223
10.4;8.4 Substrate Transport;224
10.5;8.5 Glycolysis;225
10.6;8.6 The Pentose Phosphate Pathway;231
10.7;8.7 Gluconeogenesis;232
10.8;8.8 Trehalose, Glycogen, and Cell Wall Glucans;233
10.9;8.9 Regulation;234
10.10;8.10 Metabolic Modelling and Functional Genomics;237
10.11;8.11 Concluding Remarks;239
10.12;References;239
11;9 Yeasts as Biocatalysts;250
11.1;9.1 Introduction;250
11.2;9.2 Immobilized Yeast Cells and Winemaking;257
11.3;9.3 Ethanol Production;261
11.4;9.4 Brewing;267
11.5;9.5 Fruit Wines;273
11.6;9.6 Cider;274
11.7;9.7 Vinegar;275
11.8;9.8 Dairy Products;277
11.9;9.9 Aroma;279
11.10;References;280
12;10 Production of Antioxidants, Aromas, Colours, Flavours, and Vitamins by Yeasts;291
12.1;10.1 Introduction;291
12.2;10.2 Background and Definitions;292
12.3;10.3 Concluding Remarks and Future Outlook;325
12.4;References;326
13;11 Food and Beverage Spoilage Yeasts;341
13.1;11.1 Introduction;341
13.2;11.2 Definitions;342
13.3;11.3 Which Foods are Prone to Yeast Spoilage?;344
13.4;11.4 Symptoms of Yeast Spoilage;346
13.5;11.5 Economic Effects of Yeast Spoilage;350
13.6;11.6 Which Yeasts Cause Spoilage and What are the Properties of the Successful Spoilage Yeasts?;352
13.7;11.7 Factors Comprising Preservation Systems;353
13.8;11.8 Spoilage Yeast Ecology;366
13.9;11.9 Future Trends in Yeast Spoilage;372
13.10;References;375
14;12 The Public Health and Probiotic Significance of Yeasts in Foods and Beverages;386
14.1;12.1 Introduction;386
14.2;12.2 Yeasts and Foodborne Gastroenteritis;387
14.3;12.3 Yeasts as Opportunistic Pathogens;388
14.4;12.4 Allergic and Other Adverse Responses to Yeasts;391
14.5;12.5 Yeasts as Probiotics;393
14.6;12.6 Other Health and Nutritional Benefits;395
14.7;12.7 Conclusion;395
14.8;References;396
15;13 The Development of Superior Yeast Strains for the Food and Beverage Industries: Challenges, Opportunities and Potential Benefits;403
15.1;13.1 Introduction: Who is Moulding Whom?;403
15.2;13.2 Genetically Engineering Yeasts for Improved Performance and Product Quality;408
15.3;13.3 GM Industrial Yeasts of the Future;430
15.4;13.4 General Conclusion;435
15.5;Acknowledgements;436
15.6;References;436
16;Index;449

Leseproben

Chapter 5 Physiological and Molecular Responses of Yeasts to the Environment (p. 111-112)

GRAEME M. WALKER 1 AND PATRICK VAN DIJCK 2

1 Division of Biotechnology &, Forensic Science, School of Contemporary Sciences, University of Abertay Dundee, Bell Street, Dundee DD1 1HG, UK (e-mail: [e-mail])
2 Flanders Interuniversity Institute for Biotechnology, Department of Molecular Microbiology, VIB10, Laboratory of Molecular Cell Biology, K.U. Leuven, Institute of Botany &, Microbiology, Kasteelpark Arenberg 31, 3001 Leuven, Belgium (e-mail: [e-mail])

5.1 Introduction

Understanding the ways by which yeasts respond to changes in their physicochemical environment is very important in the food and beverage industries. For example, it is important for the maintenance of yeast viability and vitality in the production and utilisation of yeasts for food and fermentation processes, and it is additionally important for the control of yeasts that act as spoilage agents of foods and beverages. In the former situation, yeasts are confronted with several environmental stresses including insults caused by changes in temperature, pH, osmotic pressure, ethanol concentration and nutrient availability that individually or collectively can deleteriously affect yeast physiology. These changes may result in lowered yeast growth yield and impaired fermentation performance. In the case of food spoilage yeasts, such organisms have adapted to survive stress caused by low temperature and oxygen levels, anhydrobiosis and high salt/sugar concentrations and their effective elimination is often based on measures to counteract the inherent stress tolerance of these yeasts. Chapter 11 covers food spoilage yeasts in more detail.

The present chapter describes both physiological and molecular aspects of stress on yeast cells and will focus on yeasts’ responses to changes in their environment which are pertinent in situations where survival of the yeast is both desirable (e.g. industrial fermentations) and undesirable (e.g. foods and beverages spoilage). The stresses of particular relevance for the food industry are thermostress, pH shock, osmostress, nutrient starvation, ethanol toxicity, oxidative stress, prolonged anaerobiosis, and exposure to chemical preservatives. This chapter will not review biologically related stress factors in yeasts such as cellular ageing, genotypic changes and competition from other organisms, the last of these having been dealt with in Chap. 4.

5.2 Yeast Nutrition and Growth
5.2.1 General Comments About Cell Physiology of Important Food Yeasts

The premier industrial yeast Saccharomyces cerevisiae is widely employed in the production of foods and fermented beverages. As such, it is by far the most economically important microorganism known to mankind. The metabolic activities of S. cerevisiae have been exploited for millennia in the leavening of bread and in the fermentation of cereal wort and grape must – these activities will continue to be exploited for future millennia. Why has S. cerevisiae found such dominance in baking and alcoholic beverage production? The reasons lie both in the ability of numerous ""industrial"" strains of S. cerevisiae to effectively transform sugars into ethanol, carbon dioxide and numerous secondary flavour compounds and it’s ability to withstand stress caused primarily by temperature, osmotic pressure, ethanol toxicity and competitive bacteria and wild yeasts. Figure 5.1 summarises major stresses encountered by industrial fermentation (brewing) yeast strains. Of course, most yeasts are similarly able to ferment sugars, but they may not be able to tolerate the rigours of a large-scale industrial fermentation plant. S. cerevisiae is clearly able to do so and has found niches well-suited to it’s physiological behaviour in wineries and fermentation plants (Martini 1993, Vaughan-Martini and Martini 1995). In short, S. cerevisiae is arguably the most resilient industrial yeast that we currently have at our disposal. Nevertheless, new approaches to improve stress-tolerance of S. cerevisiae have been developed with potential benefits for food and beverage production processes (Chap. 13).

Stress-tolerance attributes in other yeast species also impact significantly in foods and beverages. Several non-Saccharomyces yeasts have also found beneficial production applications, whilst some species are detrimental after production in storage situations, especially with regard to yeast spoilage of high-sugar and high-salt foods. Some examples of stress-tolerant yeasts important in both food production and spoilage are listed in Table 5.1.